# Sum、Max、MIN、Count、Avg
# res = Book.objects.aggregate(Sum("price"))
# res = Book.objects.aggregate(Max("price"))
# res = Book.objects.aggregate(Min("price"))
# res = Book.objects.aggregate(Count("price"))
# res = Book.objects.aggregate(Avg("price"))

# res = Book.objects.aggregate(Avg("price"), Min("price"), Max("price"))
# 结果为：平均值、最小值、最大值
